The following glossary was prepared to help the consumer become familiar with
many of the common terms used in clinical trials.
(Adverse Event.) An
unwanted effect caused by the administration of drugs. Onset may be sudden or
develop over time (See ).
Organizations and groups that actively support
participants and their families with valuable resources, including
self-empowerment and survival tools.
In the U.S., the Food
and Drug Administration (FDA) must approve a substance as a drug before it can
be marketed. The approval process involves several steps including pre-clinical
laboratory and animal studies, clinical trials for safety and efficacy, filing
of a New Drug Application by the manufacturer of the drug, FDA review of the
application, and FDA approval/rejection of application
Any of the treatment groups in a randomized
trial. Most randomized trials have two "arms," but some have three "arms," or
even more (See ).
1. Information gathered at
the beginning of a study from which variations found in the study are measured.
2. A known value or quantity with which an unknown is compared when measured or
assessed. 3. The initial time point in a clinical trial, just before a
participant starts to receive the experimental treatment which is being tested.
At this reference point, measurable values such as CD4 count are recorded.
Safety and efficacy of a drug are often determined by monitoring changes from
the baseline values.
When a point of view prevents impartial judgment on issues relating to the
subject of that point of view. In
clinical studies, bias is controlled by blinding and randomization (See
A randomized trial is "Blind" if the participant
is not told which arm of the trial he is on. A clinical trial is "Blind"
if participants are unaware on whether they are in the experimental or
control arm of the study; also called masked. (See and
Pertaining to or founded on
observation and treatment of participants, as distinguished from theoretical or
A medical researcher in charge of carrying out a clinical
A clinical trial is a research study to answer
specific questions about vaccines or new therapies or new ways of using known
treatments. Clinical trials (also called medical research and research studies)
are used to determine whether new drugs or treatments are both safe and
effective. Carefully conducted clinical trials are the fastest and safest way
to find treatments that work in people. Trials are in four phases: Phase I tests
a new drug or treatment in a small group; Phase II expands the study to a larger
group of people; Phase III expands the study to an even larger group of people;
and Phase IV takes place after the drug or treatment has been licensed and marketed.
In epidemiology, a group
of individuals with some characteristics in common.
A clinical trial conducted primarily through primary-care physicians rather
than academic research facilities.
A method of providing experimental
therapeutics prior to final FDA approval for use in humans. This procedure is
used with very sick individuals who have no other treatment options. Often,
case-by-case approval must be obtained from the FDA for "compassionate use" of
a drug or therapy.
Broad range of healing philosophies, approaches, and therapies that
Western (conventional) medicine does not commonly use to promote
well-being or treat health conditions. Examples include acupuncture,
herbs, etc. Internet Address: .
Refers to maintaining the confidentiality of trial participants
including their personal identity and all personal medical
information. The trial participants' consent to the use of records for
data verification purposes should be obtained prior to the trial and
assurance must be given that confidentiality will be maintained.
circumstance when the use of certain treatments could be harmful.
A control is the nature of the intervention control.
The standard by which
experimental observations are evaluated. In many clinical trials, one
group of patients will be given an experimental drug or treatment, while
the control group is given either a standard treatment for the illness or a
placebo (See and
Control is a
standard against which experimental observations may be evaluated. In clinical
trials, one group of participants is given an experimental drug, while another
group (i.e., the control group) is given either a standard treatment for the
disease or a placebo.
An independent committee, composed of community representatives and clinical
research experts, that reviews data while a clinical trial is in progress to
ensure that participants are not exposed to undue risk. A DSMB may recommend
that a trial be stopped if there are safety concerns or if the trial objectives
have been achieved.
Refers to trials
that are are conducted to find better tests or procedures for diagnosing a
particular disease or condition. Diagnostic trials usually include people who
have signs or symptoms of the disease or condition being studied.
A clinical trial in
which two or more doses of an agent (such as a drug) are tested against each
other to determine which dose works best and is least harmful.
A clinical trial
design in which neither the participating individuals nor the study staff knows
which participants are receiving the experimental drug and which are receiving
a placebo (or another therapy). Double-blind trials are thought to produce
objective results, since the expectations of the doctor and the participant
about the experimental drug do not affect the outcome; also called double-masked
study. See ,
of the effect of a drug when administered with another drug. The effect may be
an increase or a decrease in the action of either substance, or it may be an
adverse effect that is not normally associated with either drug.
(Of a drug or treatment). The
maximum ability of a drug or treatment to produce a result regardless of
dosage. A drug passes efficacy trials if it is effective at the dose tested and
against the illness for which it is prescribed. In the procedure mandated by
the FDA, Phase II clinical trials gauge efficacy, and Phase III trials confirm
it (See ,
Summary criteria for participant selection; includes Inclusion and Exclusion
criteria. (See )
Based on experimental data,
not on a theory.
Overall outcome that the
protocol is designed to evaluate. Common endpoints are severe toxicity,
disease progression, or death.
The act of signing up participants
into a study. Generally this process involves evaluating a participant with respect to
the eligibility criteria of the study and going through the
The branch of medical
science that deals with the study of incidence and distribution and control of
a disease in a population.
Refers to any of the
FDA procedures, such as compassionate use, parallel track, and treatment IND
that distribute experimental drugs to participants who are failing on currently
available treatments for their condition and also are unable to participate in
ongoing clinical trials.
A drug that is not
FDA licensed for use in humans, or as a treatment for a particular condition
U.S. Department of Health and Human Services agency responsible for ensuring
the safety and effectiveness of all drugs, biologics, vaccines, and medical
devices, including those used in the diagnosis, treatment, and prevention of
HIV infection, AIDS, and AIDS-related opportunistic infections. The FDA also
works with the blood banking industry to safeguard the nation's blood supply.
Internet address: .
A supposition or assumption
advanced as a basis for reasoning or argument, or as a guide to experimental
medical or social standards determining whether a person may or may not be
allowed to enter a clinical trial. These criteria are based on such factors as
age, gender, the type and stage of a disease, previous treatment history, and
other medical conditions. It is important to note that inclusion and exclusion
criteria are not used to reject people personally, but rather to identify
appropriate participants and keep them safe.
The process of
learning the key facts about a clinical trial before deciding
whether or not to participate. It is also a continuing process throughout the
study to provide information for participants. To help someone decide whether
or not to participate, the doctors and nurses involved in the trial explain the
details of the study.
A document that describes
the rights of the study participants, and includes details about the study,
such as its purpose, duration, required procedures, and key contacts. Risks and
potential benefits are explained in the informed consent document. The participant
then decides whether or not to sign the document. Informed consent is not a contract,
and the participant may withdraw from the trial at any time.
committee of physicians, statisticians, researchers, community advocates, and
others that ensures that a clinical trial is ethical and that the rights of
study participants are protected. All clinical trials in the U.S. must be
approved by an IRB before they begin. 2. Every institution that conducts or
supports biomedical or behavioral research involving human participants must, by
federal regulation, have an IRB that initially approves and periodically reviews
the research in order to protect the rights of human participants.
Analysis of clinical
trial results that includes all data from participants in the groups to which
they were randomized (See )
even if they never received the treatment.
The generic name of the precise intervention being studied.
Primary interventions being studied: types of interventions are Drug,
Gene Transfer, Vaccine, Behavior, Device, or Procedure.
new drug, antibiotic drug, or biological drug that is used in a clinical
investigation. It also includes a
biological product used in vitro
for diagnostic purposes.
The knowledge of intervention assignment. See
Study of the
natural development of something (such as an organism or a disease) over a
period of time.
application submitted by the manufacturer of a drug to the FDA - after clinical
trials have been completed - for a license to market the drug for a specified
A drug prescribed
for conditions other than those approved by the FDA.
trial in which doctors and participants know which drug or vaccine is being
An FDA category that
refers to medications used to treat diseases and conditions that occur rarely.
There is little financial incentive for the pharmaceutical industry to develop
medications for these diseases or conditions. Orphan drug status, however,
gives a manufacturer specific financial incentives to develop and provide such
Review of a clinical trial by experts
chosen by the study sponsor. These
experts review the trials for scientific merit, participant safety, and ethical
The processes (in a
living organism) of absorption, distribution, metabolism, and excretion of a
drug or vaccine.
Initial studies to
determine the metabolism and pharmacologic actions of drugs in humans,
the side effects associated with increasing doses, and to gain early evidence
of effectiveness; may include healthy participants and/or patients.
clinical studies conducted to evaluate the effectiveness of the drug
for a particular indication or indications in patients with the disease
or condition under study and to determine the common short-term side
effects and risks.
and uncontrolled trials after preliminary evidence suggesting effectiveness
of the drug has been obtained, and are intended to gather additional information
to evaluate the overall benefit-risk relationship of the drug and provide and
adequate basis for physician labeling.
studies to delineate additional information including the drug's risks,
benefits, and optimal use.
A placebo is an inactive pill,
liquid, or powder that has no treatment value. In clinical trials, experimental
treatments are often compared with placebos to assess the treatment's
effectiveness. (See ).
A method of investigation
of drugs in which an inactive substance (the placebo) is given to one group of
participants, while the drug being tested is given to another group. The
results obtained in the two groups are then compared to see if the
investigational treatment is more effective in treating the condition.
A physical or emotional
change, occurring after a substance is taken or administered, that is not the
result of any special property of the substance. The change may be beneficial,
reflecting the expectations of the participant and, often, the expectations of
the person giving the substance.
Refers to the testing of
experimental drugs in the test tube or in animals - the testing that occurs
before trials in humans may be carried out.
to trials to find better ways to prevent disease in people who have never had
the disease or to prevent a disease from returning. These approaches may include
medicines, vaccines, vitamins, minerals, or lifestyle changes.
A study plan on which all
clinical trials are based. The plan is carefully designed to safeguard
the health of the participants as well as answer specific research questions. A
protocol describes what types of people may participate in the trial; the
schedule of tests, procedures, medications, and dosages; and the length of the
study. While in a clinical trial, participants following a protocol are seen
regularly by the research staff to monitor their health and to determine the
safety and effectiveness of their treatment (See
Refers to trials that explore ways to improve comfort and quality of life for
individuals with a chronic illness.
A method based on chance by which study participants are
assigned to a treatment group. Randomization minimizes the differences among
groups by equally distributing people with particular characteristics among all
the trial arms. The researchers do not know which treatment is better. From
what is known at the time, any one of the treatments chosen could be of benefit
to the participant (See ).
A study in which
participants are randomly (i.e., by chance) assigned to one of two or more
treatment arms of a clinical trial. Occasionally placebos are utilized. (See
The period during which a trial
is attempting to identify and enroll participants. Recruitment activites can include
advertising and other ways of solicting interest from possible particpants.
Indicates the current stage of a trial, whether it is planned, ongoing, or completed.
Possible values include:
- Not yet recruiting: participants are not yet being recruited or enrolled
- Recruiting: participants are currently being recruited and enrolled
- Enrolling by invitation: participants are being (or will be) selected from a predetermined population
- Active, not recruiting: study is ongoing (i.e., patients are being treated or examined), but enrollment has completed
- Completed: the study has concluded normally; participants are no longer being
examined or treated (i.e., last patient's last visit has occurred)
- Suspended: recruiting or enrolling participants has halted prematurely but potentially will resume
- Terminated: recruiting or enrolling participants has halted prematurely and
will not resume; participants are no longer being examined or treated
- Withdrawn: study halted prematurely, prior to enrollment of first participant
risk to individual participants versus the potential benefits. The risk/benefit
ratio may differ depending on the condition being treated.
Refers to trials which
test the best way to detect certain diseases or health conditions.
Any undesired actions or
effects of a drug or treatment. Negative or adverse effects may include
headache, nausea, hair loss, skin irritation, or other physical problems.
Experimental drugs must be evaluated for both immediate and long-term
side effects (See ).
A study in which one party,
either the investigator or participant, is unaware of what medication the participant
is taking; also called single-masked study. (See
currently in wide use and approved by the FDA, considered to be effective in
the treatment of a specific disease or condition.
Treatment regimen or
medical management based on state of the art participant care.
that an event or difference occurred by chance alone. In clinical trials, the
level of statistical significance depends on the number of participants studied
and the observations made, as well as the magnitude of differences observed.
A primary or secondary
outcome used to judge the effectiveness of a treatment.
The primary investigative
techniques used in an observational protocol; types are Purpose, Duration,
Selection, and Timing.
An adverse effect produced by a
drug that is detrimental to the participant's health. The level of
toxicity associated with a drug will vary depending on the condition which the
drug is used to treat.
IND stands for
Investigational New Drug application, which is part of the process to get approval
from the FDA for marketing a new prescription drug in the U.S. It makes
promising new drugs available to desperately ill participants as early in the
drug development process as possible. Treatment INDs are made available to
participants before general marketing begins, typically during Phase III
studies. To be considered for a treatment IND a participant cannot be eligible
to be in the definitive clinical trial.
trials which test new treatments, new combinations of drugs, or new approaches
to surgery or radiation therapy.
CenterWatch, Inc. Patient Resources: Glossary.
ECRI (formerly the Emergency Care Research Institute).
Eli Lilly and Company: Lilly Clinical Trials Glossary.
MediStudy.com Inc: ClinicalTrials: A-Z Glossary.
National Cancer Institute: